A secondary battery (accumulator battery) such as a lithium-ion battery or a nickel-metal-hydride battery grows in importance as a built-in vehicle power supply or a power supply for a personal computer and a portable terminal. A secondary battery has a structure in which a wound body having a positive electrode sheet, a separator and a negative electrode sheet wound in a layered state in a housing.
For example, according to the method for manufacturing a secondary battery disclosed in Patent Literature 1, after hot pressing of a wound body, the wound body is accommodated in a housing and then initial charging is performed. Specifically, as shown in FIG. 5, the upper and lower surfaces of a wound body 101 are hot-pressed. Then, as shown in FIG. 6, the hot-pressed wound body 101 is accommodated in a housing 102, and further electrolyte 103 is filled into the housing 102. Finally, as shown in FIG. 7, initial charging is performed, confining the upper and lower surfaces of the housing 102 in which the wound body 101 and the electrolyte 103 are accommodated. In this manner, by hot pressing of the wound body, it is possible to reduce the thickness of the wound body and achieve easier accommodation into the housing and size reduction of the secondary battery.